Shaft actuated snap action mechanism for reciprocating expansible chamber motors



Oct. 12, 1948. c s cc 2.451,449

SHAFT ACTUATED SNAP ACTION MECHANISM FOR.

RECIPROCATING EXRANSIBLE CHAMBER MOTORS 5 Sheets-Sheet 1 Filed Oct. 23,1945 ATTURA/EJ/ 1 48- c. R. SACCHINI- 5 SHAFT ACTUATED SNAP ACTIONMECHANISM FOR RECIPROCATIHG EXPANSIBLE CHAMBER MOTORS Filad Oct. 23,1945 5 Sheets-Sheet 2 L38 34 7; 85 /07 [4T0 706 85 02 /00 8/ 96 86 8/ lAfro/ruff Oct. 12, 1948. 7' Q c. R. SACCHINI SHAFT 'ACTUATED SNAP ACTIONMECHANISM FOR RECIPROCATING EXPANSIBLE CHAMBER MOTORS Filed on. 2:5.1945 5 Sheets-Sheet 4 Patented Oct. 12, 1948' UNITED STATE s' PATENToFncs SHAFT ACTUATED SNAP ACTION MECHA- NISM FOR REOIPROCATINGEXPANSIBLE CHAMBER MOTORS Columbus R. Sacchini, Willoughby, Ohio,assignor to The Marquette Metal Products Company, Cleveland, Ohio, acorporation of Ohio Application October 23, 1945, Serial No. 624,072

I supplied with operating fluid under relatively low pressure and whensupplied with fluid under extremely high pressure. Although hydraulicfluid is contemplated as the operating medium, the motor may be drivenby air or other gaseous fluid.

16 Claims. (Cl. 121-164) portion against which a moving part of the snapaction mechanism is apt to slide.

Other objects and advantages will become apparent from the followingdescription wherein reference is made to the drawings in which:

Fig. 1 is a rear end view of the motor with the cover removed showingthe snap action toggle mechanism;

Fig. 2 is a fragmentary sectional view taken generally as indicated bythe line 2-2 of Fig. 1:

Fig. 3-.is a perspective view of a push rod for I operating the valves;

In the copending patent application of John H. w I

Galley and Leroy J. Carey, Serial No. 548,692, filed August 9, 1944,there is described a fluid motor of the same general type as thatdescribed herein, and the present motor possesses all of the advantagesof the said prior motor. In addition, the toggle mechanism.

the present motor has an improved and simplified snap action mechanismfor operating the valves. The housing or body of the present motor is soarranged that the fluid passages are more simply formed and require nosealing plugs. Modifications are described in which the power take-oflshaft is driven more slowly than the shaft operating the snap actionmechanism so that extremely short stroke operation of a wiper bladedirectly, driven by the power take-ofl'shaft is possible. Other improvedfeatures will be discussed in the description of the illustrated forms.

An object of the present invention is to provide a new and/or improvedfluid motor.

Another object is to provide an improved valve mechanism for a fluidmotor.

A correlative object is to provide. an improved reversing or snap actiontoggle mechanism for operating a fluid control valve means.

A further object is to provide a fluid motor having a power take-oilshaft driven with alternate rotary motion and in which the angle ofmovement of the shaft between reversals can be made extremely small.

Still another object is to provide a housing for a fluid motor includinga plurality of fluid passages leading to and from valve and pistonchambers and which may be readily drilled but none of which passagesrequire the use of plugs for closing ofl end portions.

An additional object is to provide a composite closure member for arecess containing a snap action mechanism and having a wear resistingFig. 4 is a view similar to Fig. 1 but showing the valve mechanism insection, as indicated by the line l4 of Fig. 5, and the fluid passagesand in which the booster spring for the snap action toggle mechanism hasbeen omitted;

Figs. 5 and 6 are sectional views taken generally as indicated by thelines 5-5 and 6-8, respectively, of Figs. 4 and 5, respectively;

Fig. 7 is a detail view of a modified spring for Fig. 8 is a fragmentarysectionalized view of a modified motor;

Fig. 9 is a fragmentary partly diagrammatic front end view of a furthermodification;

Fig. 10 is a fragmentary sectional view taken I generally along the lineIll-l0 of Fig. 9; and

Figs. 11 to 14 are diagrammatic views showing the operation of the snapaction toggle mechanism.

The motor operates properly in any turned position, hence such terms asfront and rear, left and right, are not to be considered restrictive inany sense.

Considering the embodiment of Figs. 1 to 6. and referring particularlyto Fig. 1, a housing for the motor comprises a body member In which ispreferably formed of a light, non-ferrous metal or a suitable plastic,appropriately bored to accommodate the working parts, and irregularlyshaped to provide a minimum of wall thickness throughout. A hollow,valve-mechanism-con- 'taining portion ll of the body I 0 is closed atitsopposite ends by respective castellated plugs l2 constituting a partof the valve mechanism (Fig. 4), and a hollow, piston'conta'ining bodyportion I4 is closed at its opposite ends by respective cas'tellatedplugs l5. Operating fluid which enters the motor under high pressure ata port l6 (marked ln") flows to the valve mechanism alternately throughpassages (to be described) formed within respective upwardly divergingbody portions [9 and is later-discharged at a port l8 (marked out").

A snap action mechanism a (ma. 1, a, 4 and 5) disposed within a recess2| formed in a side wall of the body II is driven by a power take-oi!shaft 22 (Figs. 2 and 5) and operates the valve mechanism which isarranged to control the reciprocation of a piston assembly 24 (Figs. 2,5,

and 6) and which in turn drives the shaft22.

The shaft 22 is rotatably supported in a bearing assembly 22 comprisinga bushing 25 (Pig. 5)

and may have a longitudinally serrated outer end portion 26 forreceiving a windshield wiper drive arm (not shown) which may be held inposition vided with a pair of axially spaced, annular,

shouldered portions seating, respectivelyan elastic packing ring 3| anda washer 32. The outer marginal portion of the washer 32 engages thering 3| with adjustable pressure provided by a collar 34 threaded intothe counterbore 29 and having an inturned flange portion 35 bearingagainst the washer 32.

A packing ring 26 having a c-shaped cross section with inner and outerannular wall portions defining a channel 38 is compressed between areduced portion 39 of the shaft 22 and the side wall of a counterbore 40formed at the inner end portion of. the bushing 25. As shown, thechannel 38 opens inwardly toward an annular retainer 4| having its outermarginal portion disposed between counterbore 29 and having its innermarginal portion bearing against a flange 42 formed on. the

shaft 22. The retainer 4| has a plurality of circumferentially spacedfluid conducting openings 44 for fully exposing the inner face of thepacking ring to fluid within the housing.

An intermediate portion of the opening 20 defines a working space 45 fora pinion 46 which is mounted on a noncircular (e. g. squared) portion 41of the shaft 22. A longitudinally serrated inner end portion 48 of theshaft 22 is received in adjusted turned position within a complementarygrooved bore of a hub portion 49 of a drive plate 50 constituting aportion of the snap action mechanism 20. The hub 49 is'rotatablysupported by a flanged bushing 5| pressed into a reduced extension ofthe opening 30, suitable ports 49' being provided in the hub to permitthe operating fluid of the motor to lubricate the bushing 5|. Axialmovement of the shaft 22 outwardly of the body It is preventedby-abutment of the flange 42 against the retainer 4| and inwardly byabutment of the pinion 46 against the flange portion of the bushing ii.

the flange 28 and the bottom of the of axially spaced, transverse bores50 through the rack member 52 intersect the bore 56 and are open to aregionat atmospheric pressure (outlet 59, Fig. 5 described later). Thepiston assembly 24 is slidably received for reciprocation within asleeve 60 of bronze or other "bearing" alloy pressed into a transversecylinder bore 83 in the body portion l4 and intersecting the workingspace 45, the sleeve being provided with an open- 'theinner end portionsof which define respective spherically contoured valve seats 64complementary-to a pair of safety relief ball valves 65 normally held inseated position thereon by a helical compression spring .8 interposedbetween the y balls. The rack member 24, intermediate of its endportions, is of generally rectangular cross section having a toothedupper surface but having a curved lower surface and cylindrical andportions complementary to the inner wall of the piston sleeve as shownin Figs. 5 and 6. The castellated plugs (5 which seal the bore 63 haveinternal recesses and are threaded respectively into counterbores 53"formed at opposite ends of the bore,'suitable annular packings 69 beingreceived within shouldered recesses on the plugs and compressed againstthe bottoms of the re spective counterbore II are thereby formed atopposite ends of the piston assembly24. Central bosses 12 in theinternal recesses of the plugs l5 serve as overtravcling stops for thepiston assembly 24 when the motor mechanism is adjusted for maximumstroke operation.

Referring to-Fig. 4, a pair of coaxial valve bores 14 within the bodyportion II and opening into the recess 2| respectively receive a'pair ofvalve guides in the form of sleeves 15 and ll.

The valve assembly additionally comprises a pair of preferably similarvalve plungers 18' and 19 slidably received for reciprocation in thesleeves 15 and 15, respectively. The valve plungers are in a sensefree-floating although caused to move simultaneously in the samedirection as though interconnected. The outer end portions of the bores14 are counterbored andthreaded to receive, respectively, thecastellated plugs l2, reduced inner end portions of which are pilotedwithin the respective valve sleeves l5 and It to assist in holding thesleeves in coaxial relationship and centered in the respective boreportions which receive the sleeves.

Elastic ring packings 80 are received in grooves formed in the innertransverse face surfaces of shouldered portions or the plugs l2,respectively, and are compressed against the bottoms of the counterboredportions of the respective bores 14, and similar packings 8| arereceived in annular shouldered recesses formed at the outer end portionsof the valve guides 15 and I8 and are compressed against the inner facesurfaces of the plugs l2, respectively. Reduced inner endportlons of thebores 14 define annular shoulders 24 against which the inner end facesof the guides 15 and I6 bear respectively. Tubular extensions on theguides 15 and lint loosely within the reduced bore portions,respectively.

The machining dimensions between the plugsl2 and the respective valvesleeves I5 and."

circumferential groove in the left hand plug l2 Piston chambers 10 and,

communicates with the interior of the valve sleeve II through radialpassages 88 and an axial passage 88 in the plug. A pair of diametricallyopposed ports 80 and a similarpair of ports 82 permit fluid to flowbetween the interior of the sleeve-II and an annular chamber 84 definedby an intermediate reduced portion of the sleeve. Similarly, an annularchamber 88 defined by a tapered circumferential groove in-the right handplug I2 communicates with the interior of the sleeve I through radialpassages 80 and an axial passage 88 in the plug; and ports I00. I02,which correspond to the ports 00 and 92, respectively, permit fluid toflow between the interior of the sleeve I8 and a chamber I04 defined byan intermediate reduced portion of the sleeve. The valve plungers I8 andI8 have respective inner end portions of reduced diameter adapted tocooperate with a valve actuating push rod I of the snap action mechanismdescribed below.

Drive pins I08 and IN (Figs. 1 and 4) of th snap action mechanism 20 arethreaded into respective circumferentially spaced sockets formed in theouter marginal portion of the drive plate 80. If desired, additionalsockets may be provided in the manner described in the above mentionedapplication thereby to permit adjustable positioning of the drive pins I08 and I01. Rotary movement of the shaft 22 causes turning of the plate00 so that one or the other of the drive pins I08 and I0I'strikes atoggle arm I00 which has fixed thereto a stub shaft I00 (Figs. 2 and 5)rotatably received in a smooth portion of the central bore of the hub 48as a pivot for the toggle arm.

The drive plate 80, if its hub portion is removed from the serrated end48 of the shaft 22 and replaced in a different turned position on theserrations of the shaft, will cause the wiper-blade drive arm (notshown) to operate over a field centered at one side of the unit (e. g.reference plane of the line 2-2 of Fig. 1). Similar adjustment of thedrive arm on the serrated portion 20 likewise changes the fleld ofwiping operation.

The snap action mechanism 20 (of. Figs. 1 and 4) further includesatoggle or cam member H0 in the form of a circular disc which is pivotedat its upper marginal portion on a pin III extending rearwardly fromapproximately the longitudinal center of the arm I08. The arm I08 andthe cam IIO are held normally in the right hand position shown by solidlines in Figs. 1 and 4 (or in a similar left hand position) due to thebias of a helical tension spring I I2 suitably secured at its oppositeends to pins H3 and H4 respectively. The pins II! and ill have shankportions received respectively in complementary sockets formedrespectively at the upper end portion of the arm I08 and the lowermarginal por-' tionof the cam H0. The snapaction mechanism 20 may alsohave a helper spring or spring assembly including. as shown in Figs, 1and 2, a compression spring 'I I5. The lower end portion of thespring II5 is received within a spring guide or socket IIS and the upper endportion surrounds a cylindrical inner spring guide I I! which freelytelescopes-into the guide H6. The lower 'end of the spring III bearsagainst the bottom of the guide II8 which is pivoted to the body I0 asby a pin III. The upper end of the spring II5 bears against a crotchportion H0 of the guide I". A semi-circular groove in the upper face ofthe crotch H8 bears against and is retained in position by the lowercurved face of the pin II4 rod I05 for exhaust of 6 so that the guideIII may rotate relative to the pin. 1 l

Tension springs as ordinarily made are apt to break atthe attachingloops in strenuous service and, to avoid such breakage, a compressionspring I20 (Fig. 7) may besubstituted for the tension spring II2. Thespring I20 has its opposite ends received in outwardly turned endportions ,I2I. respectively, of opposing and overlapping U- shapedtension members I22 adapted to have their bight portions I28 rotatablreceived on the respective pins III and H4.

The push rod I08 (Figs. 1, 3 and 5) extends longitudinally across therecess 2i and hasgenerally square opposite end portions I24 providedwith rounded corners I28 serving asbearing lands in the valve sleevesand an enlarged intermediate portion I28 having a groove I28 in its rearface. The groove I28 has upwardly converging or oblique side wallsdefining camming surfaces I29 and I80 which cooperate with circularsurfaces of the cam II 0 as described hereinafter. Continuously openports are provided by the fiat faces of the generally square endportions of the push operating fluid axially from the valve sleeves I5and I6.

A composite, readily removable cover plate for the recess 2| (see Fig.5) comprises an outer plate member I82 and separate inner plate membersI34 and I35, the latter serving as a wear plate against which theroundedfree end of the spring supporting pin II4 may slide and preventthe circular cam I I0 of the toggle mechanism from being pulled orforced out of parallelism with the drive plate by the snap action springor springs. The sliding abutment between. wear plate and pin I I4 alsoprevents the rearward face of the circular cam from bearing on therecessed forward face of the push rod I05 in a manner to interfere withfree movement of the push rod. The pin H4 is rigid with the circularcam, but

the cam pivot on the small end of the pin I I I eneasy assembly anddisa'ssembly.

The plate members I32 and I34 may be secured together by spot welding soas to provide a continuously projecting attaching flange portion I35 forthe cover plate assembly. The flange I36 overlies the flat rear face I38of the body I0*-adjacent the recess 2| and compressesasuitable packingring I39 within a chamfered recess at the inner peripheral margin of thefiat face.:1I38. The wear plate I35 is retained in 'placerjby aperimetral flange 00f the wear plate-seated in a stepped portion of anopening in the inner plate member I34 filled by the wear plate. The wearplate I35, or at least its smooth exposed surface, is of suitable wearand corrosion resisting metal.

. I8 communicates with a horizontal passage I45 from the inner endportion of which upwardly diverging or obliquely extending passages I46and I48 within the body portions I0 lead to respective outer endportions of the valve bores 14'. An inclined passage I49 extending fromthe chamber 94 of the valve assembly to the left hand counterbore 63'(Fig. 6) ofthe piston bore 63 provides for fluid flow from the left handvalve assembly to and from the piston chamber and a similar passage I50extending from the chamber I04, to the right hand counterbore 03 (Fig.6) of the piston bore 83 provides for fluid flow from the left hand-,valve ,as-

a similar chamberglll to the ing thereof is readily accomplished throughthe respective openings for the eastellated plugs 12 of the valveassemblies and the plugs ii of the piston and cylinder assemblies,wherefore no sealing plugs are required in forming said m'ain fluidpassages.

In event either of the safety relief ball valves (Fig. 6) is unseated,as byextremely high pressure in one or the other or both of the pistonchamber I0 and II, fluid flows into the axial bore 50 of the rack member52 and out of the transverse bores 50 to the outlet 50, Fig. 5, in theinner wall of the recess. 2| whereby such excess internal pressure isrelieved. A safety valve means is thus provided which, in the eventextremely high pressure fluid is supplied to the motor, prevents damagebeing done to the motor or the apparatus driven thereby. Discharge fluidreceived in the recess 2| through the outlets 59 as well as from .theinterior of the valve sleeves I5 and I0 flows freely therefrom through ashort bottom drain passage I01 (Fig. 4) to the outlet'port I8. y

In considering the operation of the motor, the moving parts are assumedto be initially in the position shown by solid lines in'Figs. 1, 4 and 6and reference will be made to the diagrams of Figs. 11 to 14.

Operating fluid supplied in a suitable manner to the inlet port it flowsthrough the passages I45 and I06 (Fig. 4), the annular chamber 06, thepassages 08 and 89, the interior of the valve sleeve 15 at the left ofthe plunger 10, through the ports 90, the chamber 90, andthe passage II!to the piston chamber I0. Concurrently, fluid enters the passage I48 andflows through the annular chamber 95 and the passages 00 and 90 againstthe right end face of the valve plunger I9 where it becomes static sincethe plunger 10 is held in the position shown by the push rod I05 and thetoggle mechanism 20.

The high pressure fluid in the piston chamber 10 forces the rack member52 to the right from the position shown in Fig. 6, and the rack teethdrive the pinion l0 counterclockwise (Fig. 6) to efiect turning movementof the shaft 2-1. Rota-- tion of the shaft 22 counterclockwise rotatesthe index or drive plate 50 counterclockwise as shown in Figs. 1 and 4to cause the drive pin I06 to rotate the toggle arm I00 counterclockwisefrom the position shown by the solid lines against the bias of thesprings H2 and H5.

Referring to Fig. 11, it will be noted that as the toggle arm I08 ismoved by the pin I00 from the solid line initial posiiton to thearbitrarily chosen broken line position in which the t gle arm isvertical, the circular cam III has become lowered and has been rotatedclockwise about its pivot III a few degrees while being maintained inabutment with the oblique face I20 01' the push rod I05 thereby holdingthe push rod in its initial right hand position. Both the tension springI I2 and the compression spring I I! thus far resist the clockwiseturning of the cam and both springs operate to maintain the abutmentrelationship mentioned. The dotted line position of Fig. 11 is showninsolid lines in Fig. '12., and it will be seen'by comparing Fig. 4 andFig. 11 that during this portion of the cycle the cam III exerts apositive force on the push rod I00 ngainstthe static (inlet) iluidpressure on the plunger II which is opposed by equal (inlet) fluidpressure force on the plunger 10.

As the pin I00 continues to move'counterclockwise, the toggle arm I00 isfurther rotated from the solid line position of Fig. 12 until the deadcenter position of the toggle arm and the spring III has been reached asshown by broken lines in Fig. 12 and by full lines in Fig. 13. Duringthis movement of the toggle arm I00, the

cam IIO rotates a few degrees in a clockwise direction but continues toexert a positive pressure 0 on the oblique surface I20. when the deadcenter position of the spring II! is reached, the operation of thespring III in maintaining the abutment ol'the cam H0 with, the surfaceIII is neutralized, but the compression spring III continues to operateto maintain the said abutment relationship and with a reduced effectivelever arm as compared to the lever arm obtaining in the full lineposition of Fig. 12. Slight additional movement of the pin I06 in acounterclockwise direction causes the toggle arm I00 and the spring H2to pass quickly through their dead center position into the finaltripped position of the arm I08 shown by broken lines in Fig. 13 and byfull lines in Fig. 14. As soon as the toggle arm moves through its deadcenter position, the spring II! tends to pull the cam IIO clockwiseabout its pivot, but that force is initially resisted by the compressionspring 0 until the pin H4 or upper end of the spring II! is in line withthe pivot. pin III for the cam H0. After that dead center position ofthe spring H5 has been reached, the spring H2 and the spring H5 turn thecam I I0 clockwise away from the surface I20 and against the surface I30with a hammer blow. The solid lines of Fig. 13 show the position of thespring H2 and the cam H0 at the dead center position and the full'linesof Fig. 14 show the mechanism in its final left hand position. If thecompression spring II! is omitted as indicated in Figs. 4 and 5, theoperation is exactly the same as above described except that after thedead center position of the toggle arm I00 and the spring H2 (fulllines, Fig. 13) has been passed, both the toggle arm I08 and the cam IIOswing together to their final full line position of Fig. 14, the camunder these conditions then delivering a sharp blow against the lefthand oblique face I00 of the push rod I05.

For arresting the toggle arm I00 in its two extreme positions shown bysolid lines in Figs. 11 and 14, one end of the toggle arm, lower end asshown, abuts one or the other of the parallel side walls of the togglehousing recess 2|. Such arresting abutment maintains a, predeterminedstrain in the toggle spring II2; augmenting the hammer blow delivered bythe toggle member I I0 against the shoulders I19 and I00. The toggle thepush rod has been moved to valve'reversing position as described below.In the arrested positions of the toggle member I I0 (Figs. 11 and. 14)the valve actuator rod I00 is blocked by the remaining strain of bothtoggle springs, against movement in either possible direction.

The hammer blow of the cam III against the surface Ill of the push rodIII quickly moves the plunger l0 to the left to open the ports 92 and tocut off. at the ports 00, the fluid pressure-sup; plyfromtheinletportlltothepistoocnamber chamber 1| returns the piston assembly 24 to itsinitial position; and, during such movement, the

rack teeth drive the shaft 22 clockwise as viewed in Fig. 6.Consequently the drive pin I01 engages the toggle arm I 08 and returnsthe latter through its dead center position with'a snap action asbefore. The cam IIO remains in engagement with the surface I80 and holdsthe push rod I05 in its left hand position until, after the dead'centerpositions have been passed, the cam IIO- swings counterclockwiseagainstthe surface I29 with a hammer blow to force the push rod I05 to itsinitial right hand position.

When the piston assembly 24 moves to the right (Fig. 6) fluid in thepiston chamber H is discharged through the passage I50, the chamber I04,the ports I02, the segmental spaces between the push rod I05 and theguide 16, the togglecontaining recess 2|, and the discharge passage I41to the outlet port I8. Similarly, as the piston assembly 24 moves to theleft, fluid in the piston chamber is discharged through the passage I49,the chamber 94, the ports 92, the segmental spaces between the push rodI05 and the guide 10, the recess 2| and the passage I41 to the outletport I0.

In many instances it is desirable to have a windshield wiper blade sweepthrough a very small arc prior to each reversal, i. e. to have anextremely short stroke of movement which may be of the order of 35 ofarc. The minimum length of wiper blade stroke is determined by themaximum speed of operation of the snap action mechanism, and since inthe principal embodiment just described the drive plate of the snapaction mechanism is driven at the same speed as the wiper blade shaft,the extremely short strokes sometimes desired cannot be obtained. In the.modiflcation of Fig. 8 as well as of Figs. 9 and I 10, means areprovided to cause the wiper blade shaft to rotate relatively slower thanthe drive plate of the snap action mechanism. As a result of thisdifferential in speed, the wiper blade shaft travels through a smallerarc relative to the arc of travel of the drive'plate in moving from oneextreme position to the other.

In Fig. 8 a speed increasing gear train is interposed between the rackdriven pinion and the drive plate thereby to cause more rapid rotationof the drive plate relative to the speed of rotation of the wiper bladeshaft, whereas in Figs. 9 and 10 a speed reducing gear drive isinterposed between the rack driven pinion and the wiper blade shaft.

Referring to Fig. 8, a unitary body structure I00 of a fluid motor I 6|houses the piston assembly 24, a valve mechanism which is the same asthat of the principal embodiment, and a snap action mechanism I62 whichis essentially the same as the mechanism 20. The rack r'nember52 is incontinuous driving engagement with a pinion I04 which is secured on asquared end portion I05 of a power take-01f shaft I66 to the outer endof which a windshield wiper drive arm (not shown) may be secured. Theshaft I66 is rotatably supported in the bearing assembly 23 which ismounted in'a counterbored portion I61 of an flange portion I10 of theshaft I66 disposed between the pinion I64 and the retainer H of thebearing assembly 20. The flange portion I10 constitutes a gear wheelwhich is in driving engagement with a relatively smaller gear wheel I1 Isecured, as by the splined connection illustrated, on the inner endportion of a shaft I12 having a relatively larger gear wheel I14 formedintegrally at its outer or rearward end. The shaft, I12 is rotatablysupported by a flanged bushing I15 pressed into a bore 'or socket I10formed in the body I00 and opening into a recess I18 containing the snapaction mechanism I 62, The inner end portion of the socket I16 isenlarged to form a working space I19 for the gear wheel I", and the gearwheel I14 is disposed within the recess I18. I

The gear wheel I14 is in driving engagement with a relatively smallergear wheel I which is secured as by a pin key I 8| to a hollow hubportion I02 of a drive plate I84 of the snap action mechanism I62. Thehub I82 is rotatably received in a flanged bushing I84 pressed into areduced extension of the opening I68, and in turn rotatably receives in.its axial opening an elongated hub portion I85 of a toggle arm I85. Theflange portion of v the bushing I84 is rotatably received in acylindrical opening I86 formed in the rear face of the pinion I64thereby to form a bearing support for the inner'end portion of the shaftI66. Except for the above described features of the drive plate andtoggle arm, the snap action mechanism I02 is the same as the mechanism20.

If desired, transverse thrust on the drive plate I84 may be absorbed byan idler pinion I81 in continuous engagement with the gear wheel I 80diametrically opposite the gear wheel I14. The pinion I 81' has itscentral or hub portion journaled on a cylindrical pin I88 seated in abore I89 corresponding to the fluid outlet opening 59 in the body I0, aspacer washer I90 being disposed between the base of the recess I18 andthe rear face of the pinion I81. An axial opening I90 in the pin I88serves to permit exhaust of high pressure fluid from the piston chamberscorresponding to 10 and H of Fig. 6 in event the safety relief ballsbecome unseated.

Operation of the motor I60 is similar to that of the motor of Figs. 1 to6 except that the drive plate I84 rotates more rapidly with respect tothe speed of rotation of the wiper blade shaft I66 due to theinterposition of the speed increasing gear train just described.Consequently, for a given angle of rotation of the drive plate I84, thewiper blade shaft I66 turns through a relatively smaller angle than doesthe shaft 22 during the same angle of movement of the drive plate 50.Thus the angle of stroke of a wiper drive arm driven by the motor I 60can be made smaller than is possible for a wiper drive arm driven by theaction mechanism 20 and also contains the valve mechanism and the pistonassembly 2|. The

top wall of the body portion 20| is aligned with the opening 206 andintersects a longitudinal opening 2l2 in the body 20| which, in turn, I

intersects a piston bore 2" corresponding to the bore 63 of theprincipal embodiment.

The rack member 52 of the piston assembly 29 is in direct drivingengagement with a pinion 2l6 disposed within the opening 2l2 and mountedon an intermediate non-circular portion 2| 6 of a shaft 2l0. li'he outeror forward end portion of the shaft 218 is rotatably supported in abushing 2l9' pressed into a socket 220 formed in the inner face of asealing plug 22i threaded into the opening 2|2. An elastic ring packing222 is received in an annular groove formed in the plug 22l and engagesthe first few threads of the opening 212 as the plug is screwed intoposition. The shaft 2l8 has a flange portion 224 disposed between theopposing faces of the bushing 2l9' and the pinion 215 to absorb axialthrust on the shaft and is provided with a splinedor longitudinallyserrated inner or rear end portion 225 received within the complementarygrooved hub portion 49 of the drive plate 50. The hub 49 is rotatablysupported by the flanged bushing 51 which is pressed into a reducedextension of the opening 2l2.

The pinion 2l5 is in continuous driving engagement with a segmental gear2i9 mounted on an intermediate squared portion 226 of a power take-offof wiper arm shaft 228 rotatably disposed within the opening 209 of thebody por; tion 202, clearance for the gear 219 being provided by thealigned openings 206 and 2! I. The inner end portion ofthe shaft 228isrotatably supported by a bushing 229 pressed into a reduced portion ofthe opening 209 and an intermediate portion of the shaft is supported bya bushing 290. The bushing 230 has an enlarged inner end portion 23lpressed into the opening 209 and an adjacent flange p rtion 232 abuttingthe bottom of the counterbore 210. A collar 234 threaded into thecounterbore 2l0 loosely surrounds the bushing 230 and compresses anelastic ring packing 233 against the flange 232. The inner end portionof the bushing 230 is counterbored to receive a ring packing 235 havinga generally C-shaped cross section and bearing against the shaft 228.Axial thrust of the shaft 228 is absorbed by an integral flange 236disposed between the inner end face of the bushing 230 and the gear 2l9.

The operation of the motor 200 is the same as that of the principalembodiment except that the relative size of the pinion M and gear 2!!!causes the wiper drive shaft 228 to move relativeiy slower than thedrive plate 50 whereby extremely short stroke movement of a wiper blademay be obtained and at increased torque without increase in motor size.The arrangement according to Fig. has an advantage over that of Fig. 8in that there is less power transmission loss in obtaining short strokeoperation by the Fig. 10 construction.

Iclaim:

1. In a fluid operated motor, a power member moved in oppositedirections in response to reversal of supply and exhaust fluid, areversing valve and actuator member therefor. a snap aci 12 &

tion mechanism comprising a pivoted toggle arm swingable in oppositedirections about a fixed pivot. means operatively connecting the powermember and arm to swing the arm in said directions, a cooperating togglemember pivotally mounted on the toggle arm eccentric to said fixed pivotand means including a spring connected between the toggle members andmovable through a dead center position, the toggle member havingalternately operating percussion abutment connections with the valveactuator member reversibly to move the latter, and a pair of abutmentspositioned to arrest the toggle armin 0P- 'posite extreme positionsprior to occurrence of each percussion abutment onnection whilemaintaining strain in said spring.

2. In a fluid operated motor, a power member moved in oppositedirections in response to reversal of supply and exhaust fluid, areversing valve and actuator member therefor movable oppositely tovalving positions, a snap action mechanism comprising a toggle armswingable in opposite directions about a fixed supporting pivot, meansoperatively connecting the power member and arm to swing the arm in saiddirections, a

cooperating toggle member pivoted to said arm a and arranged to swingreversibly into operating abutment with the actuator member, a springconnected between the toggle arm and toggle member remotely of thesupporting pivots -there of, said spring-being movable through a deadcenter position during operation of the snap action mechanism, said togm er b ing S able about its pivot on said arm from abutment with theactuator member in one direction out of abutment therewith and intoopposite percussion operating abutment with the actuator member, and apair of abutments for arresting said toggle arm in opposite positionswhile maintaining strain in said spring.

3. In a fluid operated motor, a power member moved in oppositedirections in response to revers-al of supply andexhaus-t fluid, areversing valve mechanism for controlling supply and exhaust fluid, anactuator member therefor movable in opposite directions and having apair of oppositely facing spaced abutment, a snap action togglemechanism connected for operation by the power member and comprising atoggle arm, a

toggle member, and a spring connecting said arm and member, saidspringoperating to hold the toggle member-alternately against said abutmentswhile the toggle arm is being moved in respective directions past thedead center position of the spring, said toggle member then engagingboth abutments of the actuator member in a manner tending to retain thelatter against movement in either direction;

4. In a fluid operated motor, a cylinder and a piston reciprocatabletherein, a rotary part oscillated by the piston, reversing valve meansfor diverting operating fluid altemately to opposite ends of thecylinder, 9. reciprocatable actuating member operatively connected tothe valve means. said actuating member having spaced shoulders, an armoperatively associated with said rotary part, means pivotally supportingthe arm for oscillation by said rotary part, a cam constituting a togglemember pivoted to the arm eccentrically of the pivot of the arm andadditionally connected to the arm by a snap action spring movto hold thecam against respective shoulders while cillated by the piston, reversingvalve means for diverting operating fluid alternately to opposite endsof the cylinder, 9. reciprocatable actuating member operativelyconnected to the valve means, said actuating member having spaceddivergen-t shoulders, an arm pivotally supported for oscillation by saidrotary part, a cam in the form or a circular disc constituting a togglemember and pivoted to the arm eccentrically or the periphery of the discand eccentrically oi the pivot or the arm and additionally connected tothe arm by a snap action spring movable across a dead center positionwith reference to the arm and said pivots,=said cam being operativeagainst respective shoulders continuously until the arm. cam and springare moved past dead center positions.

6. In a fluid operated motor, a, reciprocating fluid operable powermember and reversing valve means opera-ted thereby to divert fluidalternately into operative contact with the power memher, a valveactuating mechanism comprising an oscillating arm driven by the powermember and a toggle member pivotally connected to the arm andadditionally connected therewith by a snap action spring which assumes adead center position when the arm, and toggle .member are inone relativeposition, and a compression spring having a stationary pivoted supportat one end and a support carried by the toggle member at the other end.

7. In a, fluid operated motor, a cylinder and a piston reciproc'atabletherein, a rotary part oscillated by the piston, reversing valve meansfor diverting operating fluid alternately to opposite ends of thecylinder, a reciprocatable actuating member operatively connected to thevalve means. said actuating member having spaced shoulders, an armpivotally supported for oscillation by said port at one end and asupport carried by the toggle member at the other end.

9. In a fluid operated motor, a reciprocating fluid operable powermember and reversing valve means operated thereby to divert fluidaltemately into operative contact with the power member, a valveactuating mechanism comprising an oscillating arm driven by the powermember and a toggle member pivotally connected to the arm andadditionally connected therewith by a snap action spring which assumes adead center position when the arm and toggle member are in one relativeposition, and a compression spring having a stationary pivoted supportat one end and a pivotal-support on the toggle member at the other endconcentric with the connection 01" the flrst spring with the togglemember, whereby the compression spring acts on the toggle member in thesame general direction as the snap action spring acts thereon.

10. In a fluid operated motor, a. reciprocating fluid operable powermember and reversing valve means operated thereby to divert fluidalternately into operative contact with the power member, a valveactuating mechanism comprising an oscillating arm driven by the powermember and a toggle member pivotally connected to the arm andadditionally connected therewith by a snap action spring which assumes adead center position when the arm and toggle member are in one relativeposition, and a compression spring having a statlonary pivoted supportat one end and a pivotal rotary part, a cam constituting a toggle memberpivoted to the arm eccentrically of the pivotal support of the arm andadditionally connected thereto by a snap action spring movable across adead center position with reference to'the arm and cam, said cam havingarcuate surfaces ec-.

centric to the pivot axis of the cam on the arm and operative againstsaid shoulders alternately, a compression spring having a stationarypivoted support at one end and a support carried by said cam remotely ofthe cam pivot at the other end, said sprin s acting on the cam to rotateit in opposite directions about the pivot axis of the cam from oneextreme position engaging one shoulder quickly through an intermediatepo-- sition into engagement with the other shoulder.

8. In a fluid operated motor, a reciprocating fluid operable powermember and reversing valve means operated thereby to divert fluidalternately into operative contact with the power member, a valveactuating, mechanism comprising an oscillating arm driven by the powermember and a toggle member pivotally connected to the arm andadditionally connected therewith by a snap action compression springwhich assumes a dead center position when the arm and toggle member arein one relative position, and a second compression spring having astationary pivoted supconnection with the toggle member at the other endconcentric with the point of connection of the snap action springtherewith and acting on the toggle member in the same general directionas the snap action spring acts thereon.

11. In a fluid operated motor, a reciprocating piston drivinglyconnected to a rotatable power take-oi! shaft, reversing valve mechanismfor controlling the operation of said piston, an actuator mechanism forsaid valve mechanism, said actuator mechanism being movable in oppositedirections through a dead center position with a snap action,circumferentially spaced abutments rotatable about a common axis anddriven by said piston for eflecting operation of said actuatormechanism, and means interposed between said piston and said abutmentsfor causing said abutmen'ts to rotate at a different speed from that ofsaid power take-oil shalt.

12. In a fluid operated motor, a reciprocating piston drivinglyconnected to a rotatable power take-oil shaft, reversing valve mechanismfor controlling the operation of said piston, an actuator mechanism forsaid valve mechanism, said actuaable about a common axis and driven bysaid pision for effecting operation of said actuator mechanism, and gearmeans driven by said piston and operating to cause said power take-offshaft to retate more slowly than said abutments.

13. In a fluid operated motor, a reciprocating piston drivinglyconnected to a rotatable power take-oil shaft, aligned duplex slidingvalve plungers and cooperating valve means for controlling the operationof said piston, an actuator mechanism for said valve plungers, saidmechanism being driven in opposite directions through a dead centerposition with a snap action, circumferentially spaced abutmentsrotatable for efiecting operation of said actuator mechanism, and a geartrain interposed between said shaft and said :15 abutments for rotatingsaid abutments more slowtake-oi! shait, reversingvalve mechanism forcontrolling the operation of said piston, an actuator mechanism for saidvalve plungersfsaid actuator mechanism being movable in oppositedirections through a dead center position with a snap action,circumferentially spaced abutments rotatable about a common axis anddriven by said piston for eflecting operation of said actuatormechanism, and means interposed between said piston and said powertake-off shaft for causing said shaft to rotate at a different speedfrom that of said abutments.

15. A fluid operated motor comprising a body formed with a pair ofpressure chambers and a reciprocatable power member cooperatingtherewith for operation in opposite directions by fluid admittedalternately to and exhausted from said chambers, reversing valvemechanism in said body arranged for alternately supplying and exhaustingfluid to and from the chambers, snap action toggle mechanism between thepower member and valve means and located in a recess in said body.

a cover for the recess. and a wear resisting plate 1e carried by thecover positioned for sliding, position-retaining engagement with aportion of the toggle mechanism.

16. A fluid operated motor comprising a body having a cylinder andreciprocatable piston therein, a pair of valve chambers aligned on anaxis.

parallel to said cylinder, a pair of fluid ports on an axis parallel tosaid cylinder. an inlet passage axially aligned with one of said portsand terminating substantially at the central axis of said Diflr'ofdivergent passages extending from thei minus or said inlet passage tosaid valve rs respectively, and a pair of divergent passages extendingfrom said valve chambers respectivelyto opposite ends of said cylinder.

'1 a COLUMBUS R. SACCHDII.

REFERENCES CITED The following references are of record in the flleofthis patent:

V UNITED STATES PATENTS Number Name Date I 294,807, Reese Mar. 11, 18841,567,328 Oishei Dec. 29, 1925 1,910,019 Kelly May 23, 1933 2,229,641Darling Jan. 28, 1941

